Introduction: the standard surgical procedure for the management of benign or malignant nodular thyroid disease now is total thyroidectomy. Hypocalcemia is the most frequent complication after total thyroidectomy. Measuring parathyroid hormone (PTH) is more frequently utilized now to predict those patients at risk of developing post-thyroidectomy hypocalcemia. Aim: to determine if PTH levels can predict hypocalcemia early to safely shorten hospital stay and to compare best timing for measuring PTH either intraoperative or 4 hours postoperatively. Methods: A prospective study in which fifty patients who underwent total or completion thyroidectomy were divided according to the occurrence of hypocalcemia into 2 groups, Group A with no hypocalcemia and Group B with hypocalcemia. Adjusted serum calcium was measured preoperatively and at 4, 24 and 48 h postoperatively while PTH was measured preoperatively, intraoperatively at time of skin closure and 4 hours postoperatively. Results: no significant difference in the preoperative and intraoperative data except for higher incidence of toxic goiter and thyroiditis in group B, also higher operative time. Statistically significant decline of both serum Ca and PTH in the postoperative data results. No statistically significant difference in measuring PTH intraoperatively or at 4h post thyroidectomy. Conclusion: PTH is useful, accurate and rapid predictor of post thyroidectomy hypocalcemia and can be measured up to 10 minutes after thyroid dissection and so can predict patients who can be safely discharged on the same day after operation. Disclosure: This article is not sponsored by any company, so the authors have no competing interests as defined by Nature Publishing Group, or other interests that might be perceived to influence the results and/or discussion reported in this article. Key Words: Prospective Study, Parathyroid Hormone, Hypocalcemia, Thyroidectomy